The present research work aimed to study the effects of 3 nutritional food industry by-products (orange peels, peanut skin peels and pomegranate peel) on regulating blood glucose level. 66 male adult Sprague-Dawely rats weighing 125 ± 5 g each were used. These rats were injected with alloxan for inducing diabetes. The negative control group consisted of rats fed on basal diet, while the positive control group consisted of (3 - 11) sub-groups fed on basal diet in addition to 5%, 7.5% and 10% of nutritional food industry by-products. After 4 weeks the effect of the different experimental diets on body weight gain, organs relative weight, blood glucose level, liver functions and kidney functions was recorded for the negative group and all the positive sub-groups. The results revealed that there was non-significant difference between all relative organ weights of liver, kidney and pancreas compared to control negative. Blood glucose level significantly decreased in all sub-groups compared to the control positive group.
Food processing products have become an important sanitary problem to be studied. At present, efforts have been made for converting refused materials into valuable products [
The term Diabetes mellitus is used to describe a group of conditions characterized by raised blood glucose levels (hyperglycemia) [
It has been reported that only water-soluble fiber is active on plasma glucose and lipoprotein metabolism in humans. Therefore, in practice, the consumption of legumes, vegetables, and fruits―rich in water-soluble fiber― should be particularly encouraged. The mechanisms by which dietary fiber exerts its hypoglycemic and hypolipidemic activities are unknown. However, the ability of dietary fiber to retard food digestion and nutrient absorption certainly has an important influence on lipid and carbohydrate metabolism [
The important role of dietary fiber in the treatment of diabetic patients was indicated by the pioneer studies of Kiehm et al. [
Orange peels are the thick finely-textured and orange coloured skin of oranges. Since ancient times, orange peels have been valued for their curative properties. Many highly nutritious compounds of oranges are found in the peels. Almost all the anti-cholesterol compounds in oranges are found in the peels. These compounds help combat the LDL or “bad” cholesterol in our bodies that form clots and plaque culminating in clogged heart arteries. Therefore, including orange peels to your diet can lower the total cholesterol levels in the body [
Peanuts are composed of a thick, outer shell and, when cracked open, have a nut or seed encased by a thin, papery skin. The shell and skin are often thrown out, as the nut is the tasty portion of the product. However, the skin has beneficial properties. Peanut skin extract is now a product that consumers can buy, but some peanut lovers eat the skin as part of the treat, and some peanut butters actually use the skin when producing the item [
Pomegranate peels are gaining popularity for many reasons when it comes to the fantastic health benefits they can provide. There are several uses for pomegranate peels, the peels have great potential as a supplement to our health. The peels of a pomegranate fruit contain double the antioxidants that the pulp contains, they are possibly effective against prostate cancer, diabetes, and lymphoma disease. They can maintain the correct blood pressure and they are helpful in dealing with fertility problems beside many other health benefits [
The present study aimed to investigate the effect of the food industry by-products (orange peels, peanut skin peels and pomegranate peel on the blood glucose levels in diabetic rats.
The materials used for the current study were three food industry by-products namely orange (Citrus sinenis) peels, peanut (Arachis hypogaea L) skin peels and pomegranate (Punica granatum) peels. The peels were brought form the local market, well washed and dried at 63˚C using a fan oven. They were then processed into fine powder.
Sixty-six male albino rats were purchased from the Research Institute of Ophthalmology, Giza, Egypt with average weight (125 ± 5 g) to be used for the biological evaluation. Each rat was housed in a special cage under controlled conditions. The animals were observed daily for the apparent signs such as shape, color and distribution of hair and physical activity. All rats were fed for 3 days on the standard diet for adaptation before the beginning of the experiment. Body weighed for each rat was recorded at the beginning of the experiment and once a week, and at the end of experimental period (4 weeks) each rat was weighed at the beginning of the experiment 3 days to determine the initial weight, weight once a week for 4 weeks. The diet presented to rats in special covered cups to avoid food loss. All rats were provided with water by glass tubes through wire cage and fed as needed throughout the experimental period. The relative organs weight will be calculated.
Sixty rats were injected with 150 mg/kg body weight of re-crystallized alloxan to induce hyperglycemia, after fasting overnight according to Buko et al. [
The composition of basal diet and experimental diets per 100 g for normal and diabetic rats contained 12 g casein, 10 g corn oil, 4 g salt mix, 1 g vitamin mix, 0.2 g Calcium chloride and 7.8 g corn starch. The experimental diets contained in addition 5%, 7.5% and 10% orange peels, peanut peels and pomegranate peels.
Rats were divided into 11 groups, 6 rats in each group and fed with experimental diets for consecutive 28 days as follows:
Group 1 Normal rats, were fed on basal diet as negative control (−).
Group 2 Diabetic rats, were fed on basal diet as positive control (+).
Group 3 Diabetic rats, were fed on basal diet supplemented with 5% orange peel powder.
Group 4 Diabetic rats, were fed on basal diet supplemented with 5% peanut peel powder.
Group 5 Diabetic rats, were fed on basal diet supplemented with 5% Pomegranate peel powder
Group 6 Diabetic rats, were fed on basal diet supplemented with 7% orange peel powder.
Group 7 Diabetic rats, were fed on basal diet supplemented with 7% peanut peel powder.
Group 8 Diabetic rats, were fed on basal diet supplemented with 7% Pomegranate peel powder
Group 9 Diabetic rats, were fed on basal diet supplemented with 10% orange peel powder.
Group 10 Diabetic rats, were fed on basal diet supplemented with 10% peanut peel powder.
Group 11 Diabetic rats, were fed on basal diet supplemented with 10% Pomegranate peel powder.
At the end of the experiment, rats were fasted for overnight (more than 12 hours) and anesthetized with chloroform. Blood samples were collected in clean dry centrifuge tubes from hepatic portal vein and centrifuged for 10 minutes at 3000 rpm to separate the serum, which was kept in tubes at −18˚C till analysis.
Organs WeightLiver, pancreas, spleen and kidneys of the experimental rats were carefully removed, washed in saline solution, dried and weighed. The relative organs’ weights were calculated according to the method described by Champman et al. [
Blood and liver glucose levels were determined by the method of Trinder [
Colorimetric method was used to determine AST according to Reitman and Frankel [
Colorimetric method was used to determine ALT according to Reitman and Frankel [
Urea was determined according to the method by Fawcett and Soctt [
The ammonium ions formed will be measured by the Berthelot reaction. The blue dye indophenols product reaction absorbs light between 530 nm and 560 nm proportional to initial urea concentration. The various reagents were mixed, incubated for 15 min. at 37˚C was measured the absorbance of the sample (Asample) and of the standard (Astandard) against the blank at 550 nm (530 - 570 nm). Color was stable for 5 hours. Linearity up to 200 mg/dl (33.3 mmol/L) in serum or plasma and 4 g/dl (665 mmol/L) in urine. Urea was calculated according to the following formula:
Colorimetric method was used to determine creatinine according to Barties and Bohmer [
Colorimetric method was used to determine uric acid according to the method by Caraway [
Concentration of uric acid in serum (mg/dl)
As presented in
Relative spleen weight level was 0.41% ± 0.02% g/l00g in control group. The weight levels 0.43% ± 0.01%, 0.46% ± 0.01% and 0.48% ± 0.02% were recorded for levels 5%, 7.5%, 10% of orange peel supplement, respectively. Rats fed diet supplemented with peanut skin at levels 5% and 7.5%, 10% presented the weight levels 0.45 ± 0.03 0.48 ± 0.01 and 0.53% ± 0.02% g/l00g, respectively. Pomegranate peel feeding levels 5%, 7.5% and 10% presented the weight levels 0.45% + 0.02%, 0.52% + 0.03% and 0.62% + 0.01% g/l00g, respectively a gradual increase in relative spleen weight was observed when orange peel, peanut skin or pomegranate peel level increased. It has been reported that few clinical trials have demonstrated that the intake of dietary fibre has a positive effect on the control of diabetes and body weight [
Rats fed control diet represented Alanine aminotranspherase (ALT) level 29.4 ± 2.50 U/L. Regarding orange peel feed levels 5%, 7.5% and 10%, Alanine aminotranspherase (ALT) levels were 26.4 ± 2.0 1, 24.8 ± 2.20 and 22.1 ± 2.10 U/L, respectively. Rats fed diet supplemented with peanut skin at levels 5%, 7.5% and 10% showed the levels 25.3 ± 4.16, 22.8 ± 1.12 and 19.4 ± 2.11 UIL, respectively. Alanine aminotranspherase (ALT) levels
Parameter | Control Group | Orange peel feed level | Peanut skin feed level | Pomegranate peel feed level | ||||||
---|---|---|---|---|---|---|---|---|---|---|
5% | 7.5% | 10% | 5% | 7.5% | 10% | 5% | 7.5% | 10% | ||
LW/BW (g/100g) | 2.3 ± 0.01a | 2.43 ± 0.02a | 2.48 ± 0.03a | 2.53 ± 0.02b | 2.46 ± 0.01a | 2.52 ± 0.01b | 2.57 ± 0.01b | 2.52 ± 0.03b | 2.64 ± 0.02c | 2.73 ± 0.02d |
KW/BW (g/100g) | 1.28 ± 0.04a | 1.33 ± 0.02b | 1.40 ± 0.02b | 1.48 ± 0.01b | 1.37 ± 0.03a | 1.44 ± 0.06b | 1.54 ± 0.03c | 1.43 ± 0.01b | 1.47 ± 0.02b | 1.59 ± 0.03e |
SW/BW (g/100g) | 0.41 ± 0.02a | 0.43 ± 0.01a | 0.46 ± 0.01a | 0.48 ± 0.02b | 0.45 ± 0.03a | 0.48 ± 0.01b | 0.45 ± 0.02a | 0.53 ± 0.02b | 0.52 ± 0.03b | 0.62 ± 0.01c |
LW: Liver Weight; KW: Kidney weight; SW: Spleen Weight; BW: Body Weight. *Mean ± SE; Different letters on the numbers mean significant differences at P < 0.05.
Parameter | Control Group | Orange peel feed level | Peanut skin peel feed level | Pomegranate peel feed level | ||||||
---|---|---|---|---|---|---|---|---|---|---|
5% | 7.5% | 10% | 5% | 7.5% | 10% | 5% | 7.5% | 10% | ||
AST(U/L) | 32.1 ± 0.10a | 30.1 ± 0.10a | 27.1 ± 0.11b | 24.1 ± 0.35b | 29.3 ± 0.35b | 26.1 ± 0.20b | 23.1 ± 0.20c | 27.1 ± 0.22b | 23.4 ± 0.10b | 21.3 ± 0.30c |
ALT(U/L) | 29.4 ± 2.50a | 26.4 ± 2.01b | 24.8 ± 2.20b | 22.1 ± 2.10c | 25.3 ± 4.16ab | 22.8 ± 1.12c | 19.4 ± 2.11c | 24.0 ± 2.52a | 21.8 ± 3.25b | 17.3 ± 1.10c |
ALP(U/L) | 96.4 ± 2.51a | 88.1 ± 2.05b | 83.1 ± 2.10b | 79.1 ± 2.30c | 85.1 ± 1.10b | 82.1 ± 1.40b | 75.1 ± 2.03c | 783.1 ± 1.40a | 79.1 ± 1.25b | 73.1 ± 1.10b |
AST: Aspartate aminotranspherase; ALT: Alanine aminotranspherase; (ALP): Alkalin phosphatase; *Mean ± SE; Different letters on the numbers mean significant differences at P < 0.05.
were 24.0 ± 2.52, 21.8 ± 3.25 and 17.3 ± 1.10 U/L when pomegranate peel feed levels were 5%, 7.5% and 10%, respectively. Alanine aminotranspherase (ALT) levels decreased gradually when the supplement level increased, as the detected data show.
Rats fed control diet showed Alkalin phosphatase (ALP) level 96.4 + 2.51 U/L. Alkalin phosphatase (ALP) levels were 88.1 ± 2.05, 83.1 ± 2.10 and 79.1 ± 2.30 UI, when orange peel feed levels were 5%, 7.5% and 10%, respectively. Rats fed diet supplemented with peanut skin at levels 5%, 7.5% and 10% showed the levels 85.1 ± 1.10, 82.1 ± 1.40 and 75.1 ± 2.03 U/L, respectively. When pomegranate peel feed levels were 5, 7.5 and 10% Alkalin phosphatase (ALP) levels were 83.1 ± 1.40, 79.1 + 1.25 and 73.1 + 1.10 U/L, respectively. Alkalin phosphatase (ALP) decreased markedly with the elevation of orange peel, peanut skin or pomegranate peel level in the diet. It has been reported that Consume high-quality dietary fibre: Enhance liver health with fibre, which binds to bile and eliminates fat-soluble toxins from the body [
After 2 weeks, blood glucose level was 402.2 ± 1.2 mg/dl, for control group. Rats fed orange peel supplement in the diet at levels 5%, 7.5% and 10% showed the levels 361.4 ± 2.6, 345.2 + 3.2 and 288.4 ± 3.3 mg/dl, respectively. Rats fed diet supplemented with peanut skin at levels 5%, 7.5% and 10% showed the levels 355.3 ± 3.5, 334.2 ± 3.0 and 255.3 ± 5.5 mg/dl, respectively. Rats fed diet supplemented with pomegranate peel at levels 5%, 7.5% and 10% showed the levels 342.2 ± 4.0, 3 14.4 ± 2.3 and 205.2 ± 2.1 mg/dl, respectively.
Blood glucose decreased gradually, after two weeks of feeding experimental supplements, with the increase of supplement level.
After 3 weeks of feeding control diet, blood glucose level was 368.3 + 3.5 mg/dl. For orange peel feed levels 5%, 7.5% and 10% glucose levels were 327.2 ± 5.5, 313.5 ± 3.6 and 260.2 ± 1.1 mg/dl, respectively. Rats fed peanut skin supplement 5.75 and 10% in the diet presented the levels 318.2 ± 2.6, 288.5 ± 1.0 and 238.6 ± 3.8 mg/dl, respectively. Regarding pomegranate peel feed levels 5%, 7.5% and 10%, it was observed that blood glucose levels were 286.5 ± 3.2, 270.5 ± 5.5 and 178.3 + 2.5 mg/dl, respectively. Provided data illustrate a gradual decrease of blood glucose level as orange peel, peanut skin or pomegranate peel supplement level increased.
After feeding control diet for 4 weeks blood glucose level was 388.2 ± 4.5 mg/dl. Rats fed diet supplemented with orange peel, 5%, 7.5% and 10% showed levels 288.3 ± 3.5, 257.7 ± 1.7 and 218.5 ± 3.5 mg/dl, respectively. Rats fed diet supplemented with peanut skin, recorded levels 276.2 ± 2.7, 237.5 ± 3.4 and 200.6 ± 1.5 mg/dl for levels 5%, 7.5% and 10%, respectively. Rats fed diet supplemented with pomegranate peel 5%, 7.5% and 10%, showed levels 236.3 ± 1.2, 227.2 ± 1.2 and 150.3 ± 4.5 mg/dl, respectively. Alter 4 weeks, blood glucose decreased
Intervals (weeks) | Control Group | Orange peel feed level | Peanut skin peel feed level | Pomegranate peel feed level | ||||||
---|---|---|---|---|---|---|---|---|---|---|
5% | 7.5% | 10% | 5% | 7.5% | 10% | 5% | 7.5% | 10% | ||
First Week | 392.7 ± 3.5a | 388.2 ± 1.5a | 368.4 ± 3.5a | 305.2 ± 5.5b | 372.2 ± 2.1a | 352.2 ± 2.5a | 276.4 ± 5.3a | 360.1 ± 2.5a | 340.3 ± 3.1a | 226.2 ± 2.1b |
Second Week | 402.2 ± 1.2a | 361.4 ± 2.6a | 345.2 ± 3.2b | 288.4 ± 3.3b | 355.3 ± 3.5a | 334.2 ± 3.0b | 255.3 ± 5.5c | 342.2 ± 4.0b | 314.4 ± 2.3b | 205.2 ± 2.1c |
Third Week | 368.3 ± 2.7a | 327.2 ± 5.5a | 313.5 ± 3.6a | 260.2 ± 1.1b | 318.2 ± 2.6a | 288.5 ± 1.0b | 238.6 ± 3.8b | 286.5 ± 3.2b | 270.5 ± 5.5b | 178.3 ± 2.5c |
Fourth Week | 388.2 ± 4.5a | 288.3 ± 3.5b | 257.7 ± 1.7b | 218.5 ± 3.5b | 276.2 ± 2.7b | 237.5 ± 3.4b | 200.6.1 ± 1.5c | 236.3 ± 1.2b | 227.2 ± 1.2b | 150.3 ± 4.5c |
*Mean ± SE; Different letters on the numbers mean.
gradually with the increase of experimental supplement level.
There is much evidence that diabetic patients are at high risk of cardiovascular disease and that this risk increases in the presence of one or more of the other risk factors [
The hypoglycemic properties of some food industry by-products such as pomegranate peel, peanut red hull and orange peels in this study may be attributed to one or more of its photochemical properties. The blood glucose level, liver function and kidney function were determined for the negative group and all sub-groups. The results obtained revealed that there was non-significant difference between all relative organ weights of liver, kidney and pancreas compared to control negative. Blood glucose level significantly decreased in all sub-groups compared to control positive.
The results indicated that pomegranate peel and peanut red hull can reduce blood glucose. It is highly recommended for the diabetic patients to include dietary fiber such as Pomegranate peel, peanut peel and orange peels in their diet.
The authors express their sincere gratitude to the staff member of the Department of Food Science and Technology of Gezira University, Sudan and the Research Institute of Ophthalmology, Giza, Egypt, and Department of Chemistry, Faculty of Science, Taif University, KSA; for the assistance presented by them.
Sirekhatim B.Elhardallou,Wisal A. M.Babiker,Abdel Moneim E.Sulieman,Adil AbdallaGobouri, (2015) Effect of Diet Supplementation with Food Industry By-Products on Diabetic Rats. Food and Nutrition Sciences,06,875-882. doi: 10.4236/fns.2015.610092